iv managed to get all the way up to Yosuke on my Hydraulic (getting legend achievement with him to)if i have to deal 4000+ damage and keep his focus down AND keep hitting him for 4000+ damage is a very tall order for a hyrdo.
if you go ice/shatter build you CAN hit over 4000 but by the time you can hit that dard again hes healing himself back up.
if you go hot blooded he hits you so hard that dux can't keep you up
and if someone says something about playing a different class WHAT THE POINT OF THE CLASS BEEN THERE IF IT CAN'T KILL A BOSS
I used a risky move that did so much damage, it went through all his effects and shield, and did a load of damage. Of caure thats not ALL i did to kill him, but if it werent for that i'd be long gone.